1. Field of the Invention
The present invention relates to a fastener for detachably securing lining panels, strips of trim, or the like on support panels such as the body sheet metal of motor vehicles. The fastener includes a bushing made of a hard, elastic material insertable into an aperture in the support panel and a plug secured by a head to the lining panel. The plug includes a conically tapering bulge which can be forced into the bushing. A funnel-shaped constriction in the bushing corresponding to the bulge will elastically yield under the attachment force whereby the bulge can be axially fixed with respect to the constriction. The bushing includes a flange which rests on the support panel. The bushing is anchored to the rim of the aperture in the support panel by elastically compressible legs which cooperate with the flange.
2. Description of the Prior Art
In the past the attachment of lining panels to support panels ordinarily occurred in three operational steps. First, the bushing is forced into an aperture of the support panel. Second, the plug head is anchored to the lining panel. This anchoring step adds to the cost of the attachment operation. For example, a plug head might be inserted into a keyhole-shaped clearance in the lining panel. A matching support plate or fixture, parallel to and located underneath the lining panel and the head of the plug, might be secured to the lining panel in order to axially fix the plug in the keyhole. Finally, the plug can be forced into a funnel-shaped constriction in the bushing until a bulge of the plug snaps into position behind the constriction in the bushing. The backside of the bulge is tapered allowing the plug to be removed from the bushing when force is applied in the reverse direction. The taper on the backside of the bulge is generally steeper than the taper on the leading side of the bulge. More force is required, therefore, to extract the plug, than is required to insert the plug into the bushing.
3. Problems Presented by the Prior Art
This above-described fastening principle has been practiced for many years in the motor vehicle industry. The process of first putting the fastener parts in place on the respective panels and then mutually joining the fastener parts, however, requires extensive assembly time at the factory. This expenditure of assembly line time is one of the major drawbacks of the prior art fasteners.